Publications and other reference materials referred to herein are numerically referenced in the following text and respectively grouped in the appended Bibliography which immediately precedes the claims.
Many image and video analysis algorithms demonstrate their performance in a dark room with no background lights [1] [2]. Added background lights—which vary in space, time, and spectra — create new challenges to these algorithms, by having to compensate for the presence of additional lights.
Passive solutions to these challenges compensate for the effect of the unwanted background lights by assuming a pre-known behavior of light upon objects in the scene. Spatially varying light conditions, for example, raise the challenge bar on color constancy algorithms [3] [4] [5] [6].
Active solutions use a controlled light source in order to clear the effect of the background lights in the scene. Flash no flash [7] [8] [9], for example, generates results from two captured frames: first with flash on, second with flash off, assuming a static background [10] and precise synchronization between flash and camera.
Video color correction [11] [12] and shadow removal [13] are usually treated as separate problems in the literature. Shadow removal and color correction combined could enhance the performance of many video analysis methods such as object tracking [14] and face detection [15].
It is therefore a purpose of the present invention to provide a method for creating images captured with an image sensor, such as the one used in a video camera, that are independent of light conditions.
It is another purpose of the present invention to provide a method for combining shadow correction, color correction and background removal in images captured with an image sensor in order to improve performance of smart camera systems for, inter alia, object and face recognition and detection and tele measurement of vital signs.
Further purposes and advantages of this invention will appear as the description proceeds.